Sound absorbing panel



. Feb. zo, 1934. f a D. MQNTYRE i 1,941,788

SOUND ABSORBING FANEL 'Filed Jan. 18, 1932 INVENTOR 2rd revi, eff/tyre@mM/@MMM ATTORNEYfS Patented Feb. 20, 1,934

UNITED STATES PATENT OFFICE SOUND ABSORBING PANEL Application January18, 1932. Serial No. 587,435

2 Claims. (Cl. 154.44)

This invention relates to sound absorbing panels and to the method ofmanufacturing the same.

Panels constructed in accordance with this i invention, While capable ofmany and varied uses, iind particular utility in use in connection withmotor vehicle bodies and the like for insulating, for instance, the dashso as tc prevent the noises from the engine from entering the interiorof the vehicle.

An object of this invention is to produce a panel structure including abody or ller of brous material together with, for instance, asphalt orsome other binder and powdered rubber, this body material or fillerbeing then enclosed in a casing or envelop of sheet rubber.

The characteristics of the resulting structure is such that sounds arenot. only adequately obstructed but are actually absorbed so that panelszo oi' this nature are especially eilicient in insulating motor vehiclebodies against sound.

Another object oi the invention is to so con-l struct the panels duringthe method of manufacture that provision is made for the passage throughthe panel of cables, rods, wires and other controlling or connectingmeans which customaily pass through the dash of a motor vehicle.

Still another object oi the invention is to pro.- vlde a method ofmanufacture wherein an internal pressure is set up in the panel duringmanufacture so as to hold one or both sides of the panel irmly inengagement with the mold whereupon designs in relief or intaglio may beimparted to the surface of the panels from the contacting portions ofthe mold.

The several objects, advantages and novel details of construction of theinvention will be made more apparent as this description proceeds,especlally when considered in connection with the acan companyingdrawing wherein Figure l is a transverse sectional view through a soundabsorbing panel constructed in accordance with this invention, and

Figure 2 is a sectional view through the molding apparatus.

As shown in Figure 1 the panel consists of a body `or iiller 10 composedof fibrous material.

While various types of ilbrousmaterial may be employed, jute nbre orwaste jute has been found to be particularly eilcient. Asphalt is mixedwith the brous material together with powdered rubber.

This material is enclosed in a casing or envelop consisting oi' sheetsof rubber 11 and 12. Sheets of unvulcanized rubber are preferable.

The fibrous material together with the asphalt andrubber may first beformed into sheet form before introduction into thelenvelop or casing,or it may be introduced therein in a loose form as will be hereinafterdescribed more in detail.

In Figure 2 there is illustrated a lower mold part 1S which is heated,which mold part has a recess 14 in which a sheet of unvulcanized rubberil.a is placed. This rubber sheet is of sunlcient size to permit itsmargin l1b to project 65 beyond the edges of the mold recess as clearlyshown in Figure 2. The filling material 10a is then introduced. Thislling material consists approximately ci brous material and 40% asphaltand powdered rubber. This material is spread evenly throughout the moldrecess 14 and thereafter another sheet 12P- of unvulcanized rubber isplaced in position and the edges 12b are tucked in. Then the upper moldmember 15, which is also heated, is-,brought into position to presstogether the rubber sheets l1a and 12a and the iilling material 10a.While thus under pressure the heat from the mold members vulcanizes therubber sheets and unites these sheets together at their points ofengagement.

At the same time the lling material, having been subjected to pressureand heat, the asphalt causes the brous material to bind together into asubstantially sheet-like body and the powdered rubber is melted andcompressed and combines g5 with the fibrous material to impart aninherent resiliency to the structure and to form a plurality of minuteair cells which expand somewhat when thev pressure of the mold membersis relieved with the result that a slightly compressible or resilientcellular structure is provided which acts in use to efficiently absorbsound. The rubber envelop or casingv protects the body of the panel fromdisintegration and provides a smooth or finished exterior desirable inpanels of this type, particularly when the same are used as insulationin motor vehicles.

If, during the process of manufacture, it is desirable to provide thepanel with openings 16 therethrough so that speedometer cables, controlrods, wires or the like can be passed therethrough, one of the moldparts may be provided with studs 17 having reduced end portions 18. Thuswhen the rubber sheet 11e is placed in the mold it will be provided withapertures which will be fitted over the stud 17 as illustrated in Figure2, and when the mold parts are brought together the upper rubber sheet12n will be pressed against the studs 18 to partially produce aperturesin the upper side of the' panel which may subsequently lll be pressedthrough. Thus, as seen in Figure 1 the resulting panel would be providedwith the relatively large openings or apertures 16 extendingsubstantially through the panel whereas the rubber sheet 12 will beprovided with restricted openings 16a which will tightly engage thecables, rods, wires or the like so as not to permit the passage of soundthrough the openings. vIt will be understood that the very nature of therubber sheet 12 will permit the apertures to be stretched so as toaccommodate cables, rods and the like of different size but neverthelessto tightly engage the same.

Obviously, other means may be employed Vfor providing apertures throughthe panels during the process of manufacture.

Sometimes it is desirable in panels of this nature to form designs onthe surfaces thereof, either in relief or intaglio. Because of thecompressible nature of the panel it would be difficult to produce thesedesigns faithfully. To this end,

I contemplate introducing in the mixture when it is desired to producedesigns on the panel, a small amount of bicarbonate of soda. This, underthe action of the heat of the molds, will combine with the fillingmaterial to produce a gas which will tend to expand the panel and pressthe top and bottom walls thereof against the adl jacent faces of themold members upon which, of

course, the desired designs in relief or intaglio would be inscribed.Thus, the walls of the panel, during the molding operation, would bepremed against the mold members so that the designs carried therebywould be transferred to the top and bottom walls of the panel. When thepanel is subsequently removed from the mold members and cooled, the gaswould subside.

The margin portions 11b of the sheet 11, in the finished panel, providea peripheral flange or apron 181 which can be used to adequately closethe space between the edge of the panel and the adjacent vehicle bodyparts when the panel is used to insulate the dash of a motor vehiclebody.

Having thus described my invention, what I claim is:

1. A sound absorbing panel comprising an outer covering of vulcanizedsheet rubber and a filler of fibrous material,l asphalt and powderedrubber, in substantially the proportions of 60% brous material and 40%asphalt and powdered rubber.

2. A sound absorbing panel consisting of an outer casing of vulcanizedsheet rubber and a body composed of substantially 60% jute fibre and 40%asphalt and powdered rubber.

BROUWER D. MCINTYRE.

